diff --git a/src/mkvmerge.cpp b/src/mkvmerge.cpp
index e743e760d..7acd14934 100644
--- a/src/mkvmerge.cpp
+++ b/src/mkvmerge.cpp
@@ -1415,6 +1415,7 @@ static void parse_args(int argc, char **argv) {
         exit(1);
       }
       ti.aspect_ratio = parse_aspect_ratio(argv[i + 1]);
+      ti.aspect_ratio_given = true;
       i++;
 
     } else if (!strcmp(argv[i], "-y") || !strcmp(argv[i], "--sync")) {
@@ -1529,7 +1530,7 @@ static void parse_args(int argc, char **argv) {
       ti.languages = new vector<language_t>;
       ti.sub_charsets = new vector<language_t>;
       ti.all_tags = new vector<tags_t>;
-      ti.aspect_ratio = 1.0;
+      ti.aspect_ratio = 0.0;
       ti.atracks = new vector<int64_t>;
       ti.vtracks = new vector<int64_t>;
       ti.stracks = new vector<int64_t>;
diff --git a/src/pr_generic.cpp b/src/pr_generic.cpp
index 00a9d2500..79dc2d5fd 100644
--- a/src/pr_generic.cpp
+++ b/src/pr_generic.cpp
@@ -409,7 +409,7 @@ void generic_packetizer_c::set_headers() {
       GetChild<KaxTrackVideo>(*track_entry);
 
     if ((hvideo_pixel_height != -1) && (hvideo_pixel_width != -1)) {
-      if (ti->aspect_ratio == 0.0)
+      if (!ti->aspect_ratio_given)
         ti->aspect_ratio = (float)hvideo_pixel_width /
           (float)hvideo_pixel_height;
       if (ti->aspect_ratio >
diff --git a/src/pr_generic.h b/src/pr_generic.h
index 01753b5e7..51560ee5e 100644
--- a/src/pr_generic.h
+++ b/src/pr_generic.h
@@ -89,6 +89,7 @@ typedef struct {
 
   char fourcc[5];
   float aspect_ratio;
+  bool aspect_ratio_given;
 
   vector<audio_sync_t> *audio_syncs; // As given on the command line
   audio_sync_t async;           // For this very track